Use of echocardiography in newborns with patent ductus arteriosus: a review.

Assessment of the contribution of left-to-right shunted ductal flow to the clinical state of a newborn with respiratory distress syndrome is difficult. Echocardiography has aided in the bedside diagnosis and management of these infants. M-mode echocardiography allows evaluation of left atrial dimension in both precordial and suprasternal planes, left ventricular dimension, and indices of function. M-mode echocardiography combined with saline contrast aortic injections allows a very sensitive demonstration of the presence of left-to-right shunting patent ductus arteriosus even if no murmur is present. Two-dimensional echocardiography demonstrates the physical appearance of the ductus and helps rule out associated congenital cardiac lesions. Incorporation of venous and arterial contrast injections help demonstrate flow direction as well. Range gated pulsed Doppler echocardiography helps evaluate flow characteristics and aids in differential diagnosis. In the future, ultrasonic evaluation will probably combine Doppler echocardiography with two-dimensional echocardiography allowing clearer noninvasive definition of anatomy and flow direction. None of these techniques should be used by itself. Careful clinical assessment by standard techniques along with judicious use of ultrasonic methodology should result in improved diagnosis and management.